Apparatus for making molds for the casting of dental fillings and the like.



PATENTED SEPT. 10, l90' 7.

V W. H. TAGGART. APPARATUS FOR MAKING M0 LDS FOR THE CASTING 0F DENT ANDTHE LIKE. APPLICATION FILED JULY 12 1907.

AL FILLINGS Men/227 Twaf Wm? QAM" Jiysw UNMED srA'rns PATENT onrron.

WILLIAM'H. TAGGART, OF CHICAGO, ILLINOIS.

APPARATUS FOR MAKING MOLDS Specification of Letters Patent.

FOR THE CASTING OE DENTAL FILLINGS AND THE LIKE.

Patented Sept. 10, 1907.

" Original application filedilanuary 12, 1907, Serial No. 351,918.Divided and this application filed July 12, 1907. Serial No. 383,481-

To all whom it may concern:

Be it known that I,.WILLIAM H. TAGGART, a citizen of the United States,residing at Chicago, in the county of Copk and State of Illinois, haveinvented a new and useful Improvement in Apparatus for Making Molds forthe Casting of Dental Fillings and the Like, of which the following is aspecification.

Myinvention relates to certain new and useful improvements in apparatusfor making molds for the casting of dental fillings and the like, and isfully described .and explained in the specification and shown in theaccompanying drawing, in which:

Figure his a perspective view of a tooth showing the manner" in whichthe pattern I use with my apparatus is constructed; Fig. 2 is a similarview of the pattern removed from place; Fig. 3 is a similar view of thepattern showing the sprue former attached thereto; Fig. 4. is asectional view showing the pattern, sprue former and primary coat ofmold material;,Fig. 5 is a section through the flask and its cover,showing the pattern and primary coat of mold-forming material mounted inposition; Ijig. 6 is a similar view showing thesecondary body ofmold-forming material introduced into the flask, with the cover andsprue former'removed; and

Fig. 7 is a view showing the flask inverted and the method by which thepattern is dissipated; and Fig. 8

, is a sectional view showing the flask in position for cast- Thisapplication is 'a division of an application filed on January 12, 1907,and allotted Serial No. 351,918, and it is particularly directed tothose portions of the apparatus shown insuch application whichare usedin making the mold, as distinguished fromthoso portions of the apparatuswhich are used after the mold is completed in the making of the casting.

As the first step iri the practice of my method, I form -a pattern A ofa fine grade of wax which is plastic at the temperature of the body, andwhich is purified, preferably, so as to be capable of completevolatilization under the action of heat, This pattern is made in thetooth cavity itself and in contact with the surfaces thereof, so thatits lower-surfaces conform perfectly to" 4 the, opposite teeth isassured. It will be understood,

of course, that the cavity is made without overhangs; as is the commonpractice in preparing cavities for inlay fillings either of porcelain ormetal, so that after the pattern is completed it can readily be removed,when it will appear as shown in Fig. 2.

A pointed end I) of a sprue former B is then thrust posed to heat.

into one of the surfaces of the pattern, preferably into one of theupper surfaces, where a slight inaccuracy caused by the presence of thesprue will bcbf no consequence. The sprue former B is cylindrical inform, having at one end the point b referred to, for insertion into theplastic material of the pattern, and having at the other end a reducedportion b, tho purposo of which will hereafter be explained.

After the pattern is secured totho sprue former as aforesaid, the sprueformer is used as a handle and the pattern is given a primary coat 0 ofinvesting mate; rial such as is commonly used by dentists. Theseinvesting materials consist of mixtures in various propor- ,tions ofplaster of paris, silica and other substances,

and various qualities with reference to their liability to crack and theamount which they shrink when 0X- To secure the best results as goodgrade as possible of investing material should be used, but While theuse of-a bad quality of investing material may interfere with theperfect success of my process,

the quality of the investing material has no bearing on whether or notmy invention is present. I V,

' After .the primary body of investing material is placed upon thepattern, the reduced end -b of the sprue former is inserted in acentral'perforation in a projection d of a cover D adapted to fit aflask E. By this means the pattern and primary body of mold material aresupported centrally within the flask, out of contact with the wallsthereof and in position to be completely surrounded by a secondary bodyof mold material F, also of dental investment material, which issubsequently poured By forming the mold thus in two steps, it ispossible to get perfect contact between the pattern and the moldmaterial, and any air bubbles which willbe formed as the mold materialis poured into the flask will be formed outside of the prisition in themold and leaving the mold with a hemispherical depression G in its uppersurface, which depression is adapted to serve as a crucible for themelt- 'ing of the metal, all as set forth in my application aboveidentified. The flask and moldgare then heated by means of/aburner andthe wax pattern is completely dissipated, the vapors arising therefrompassing out of the sprue hole so that the mold is left in the conditionshown in Fig. 8 with a hollow to receive the metal, which hollow is asubstantially exactduplicate of the cavity surfaces combined with thesurfaces formed 'by the upper faces of the filling or pattern, with asprue hole running from said hollow upward and terminating hollow of themold, where, when it sets, it will perfectly reproduce the fillingdesired.

I realize that considerable variation is possible in the details ofconstruction Without departing from the spirit of my invention, and I donot intend, therefore, to limit myself to the specific form herein shownand described.

I claim as new and desire to secure by Letters Patent;

1. In a device of the class described, the combination with a flask anda cover therefor, of a sprue former mounted on the cover and adapted tosupport a pattern.

2. In a device of the class described, the combination with a flask anda cover therefor, of a sprue former removably mounted on the cover andadapted to support a pattern.

In a device of the class described, the combination with a flask and a"cover therefor having a projection adapted to form a depression in themold to serve as a crucible for melting the metal, and a sprue formermounted on the projection and adapted to support a pattern.

I 4. In a device of the class described, the combination with a flaskand a cover therefor having a projection adapted to form a depression inthe mold to serve as a crucible for melting the metal, and a sprueformer removably mounted on the cover adapted to support a pattern.

5. In a device of the class described. a sprue former above identified,into the on the projection and provided with means for securing itremovably to a pattern to support the same.

6. Ina device of the class described, a sprue former having a pointedtip adapted to be inserted in a plastic pattern to support the same.

7. In a device of the class described, the combination with a sprueformer adapted, to be attached at one end to a pattern, of a flask and acover for said flask, said cover having a portion arranged to receix:the opposite end of the sprue formerto support the pattern.

8. In a device of the class described, the combination with a sprueformer adapted to be attached at one end to a pattern, of a flask and acover for said flask, said cover having an opening arranged to receive areduced end upon said sprue former to support the pattern.

9. In a device of the class described, the combination with a flask of'a cover therefor having a projection adapted to form a depression inthe mold to serve as a crucible for melting the metal, and a sprueformer adapted to be attached at one end to the pattern and at the otherend to be inserted in a suitableperforation in the projection of saidcover.

10. In a device of the class described, the combination with a flask ofa. cover therefor having a projection adapted to form a depression inthe mold to serve as a crucible for melting the metal, and a sprueformer having a reduced end adapted to be attached at one end to thepattern and to have its reduced end inserted in aperforation in thecenter of the projection of said cover.

WILLIAM H. TAGGART;

